U.S. patent application number 14/403649 was filed with the patent office on 2015-12-03 for plug-in pump.
The applicant listed for this patent is Continental Automotive GmbH. Invention is credited to Uwe Nigrin, Ngoc-Tam Vu.
Application Number | 20150345447 14/403649 |
Document ID | / |
Family ID | 49949635 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150345447 |
Kind Code |
A1 |
Vu; Ngoc-Tam ; et
al. |
December 3, 2015 |
Plug-In Pump
Abstract
A plug-in pump includes a cylinder and a pump housing, wherein
the cylinder has a cavity in which a movable piston is
accommodated, wherein a first end of the piston delimits a pump
chamber, and a second end of the piston is connected to a drive
device for the piston. An inlet valve is arranged in the cylinder,
which inlet valve connects the pump chamber to a feed line for a
first fluid, and an outlet valve connects the pump chamber to an
outlet. The pump housing has a cavity that forms a first chamber
connected to a feed line for the first fluid, and at least one
second chamber which is separated from the first chamber and which
is connected to a fluid system of a second fluid. The first chamber
is fluidically sealed off with respect to the second chamber.
Inventors: |
Vu; Ngoc-Tam; (Ludwigsburg,
DE) ; Nigrin; Uwe; (Ilmenau, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Continental Automotive GmbH |
Hannover |
|
DE |
|
|
Family ID: |
49949635 |
Appl. No.: |
14/403649 |
Filed: |
December 19, 2013 |
PCT Filed: |
December 19, 2013 |
PCT NO: |
PCT/EP2013/077331 |
371 Date: |
November 25, 2014 |
Current U.S.
Class: |
417/374 ;
417/534 |
Current CPC
Class: |
F02M 59/102 20130101;
F02M 59/027 20130101; F04B 1/0448 20130101; F02M 59/442 20130101;
F04B 53/14 20130101; F04B 53/18 20130101; F04B 9/042 20130101; F04B
19/22 20130101; F04B 53/16 20130101; F04B 17/05 20130101; F04B
1/0439 20130101; F04B 1/053 20130101; F04B 1/0421 20130101; F04B
53/10 20130101 |
International
Class: |
F02M 59/44 20060101
F02M059/44; F04B 17/05 20060101 F04B017/05; F04B 19/22 20060101
F04B019/22; F02M 59/10 20060101 F02M059/10; F04B 53/14 20060101
F04B053/14; F04B 53/16 20060101 F04B053/16; F04B 53/18 20060101
F04B053/18; F02M 59/02 20060101 F02M059/02; F04B 9/04 20060101
F04B009/04; F04B 53/10 20060101 F04B053/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2012 |
DE |
10 2012 224 317.8 |
Claims
1. A plug-in pump comprising: a cylinder having a cavity, and a
pump housing, a movable piston arranged in the cavity of the
cylinder, wherein a first end of the piston delimits a pump
chamber, and a second end of the piston is connected to a drive
device for the piston, an inlet valve arranged in the cylinder,
wherein the inlet valve connects the pump chamber to a feed line
for a first fluid, and an outlet valve that connects the pump
chamber to an outlet, wherein the pump housing has a cavity that
forms (a) a first chamber connected to a feed line for the first
fluid, and at least one second chamber, separated from the first
chamber and connected to a fluid system of a second fluid, wherein
the first chamber is fluidically sealed off with respect to the
second chamber.
2. The plug-in pump of claim 1, wherein the second end of the
piston is connected to or formed integrally with an intermediate
piece that transmits a movement of the drive device to the
piston.
3. The plug-in pump of claim 2, wherein the intermediate piece
includes a first section that projects into the first chamber, a
third section that projects into the second chamber, and a second
section that connects the first section and the third section and
projects through a connecting region, formed in the cavity between
the first chamber and the second chamber.
4. The plug-in pump of claim 3, wherein: the connecting region has
a shape of a hollow cylinder having an inside diameter that
corresponds substantially to an outside diameter of the second
section, and at least one of the inner wall of the connecting
region and the second section has a sealing element that prevents
the first and second fluids from mixing with each other.
5. The plug-in pump of claim 1, comprising at least one spring
element arranged in at least one of the first chamber and the
second chamber, wherein the at least one spring element moves the
piston and the intermediate piece in a direction in which the inlet
valve connects the feed line to the pump chamber.
6. The plug-in pump of claim 1, comprising a spring element in the
first chamber, wherein the spring element moves the piston and the
intermediate piece in a direction in which the inlet valve connects
the feed line to the pump chamber, and wherein the spring element
is supported on an underside of the cylinder head and on a spring
holder, connected to an end of the intermediate piece facing the
second end of the piston.
7. The plug-in pump of claim 14, comprising a spring element in the
second chamber, wherein the spring element moves the piston and the
intermediate piece in a direction in which the inlet valve connects
the feed line to the pump chamber, and wherein the spring element
is supported on an underside of the connecting region and on a
spring holder connected to an end of the intermediate piece facing
the drive device.
8. The plug-in pump of claim 1, wherein: the first fluid is carried
by the feed line and connecting lines in the pump housing into an
annular passage, the annular passage is formed in the connecting
region between the cylinder and the housing, and at least one side
wall of the annular passage is formed by an outer side of the
cylinder and at least one side wall of the annular passage is
formed by an outer side of the housing.
9. The plug-in pump of claim 1, wherein: the drive device is a
camshaft, and a cam of the camshaft acts on a roller tappet that
converts a rotary motion of the camshaft into a linear motion of
the piston.
10. A plug-in pump of claim 1, wherein the inlet valve is a digital
inlet valve.
11. The plug-in pump of claim 1, wherein the first fluid is a fuel
and the second fluid is a lubricating oil.
12. The plug-in pump of claim 1, wherein the cylinder is formed
from steel and the housing is formed from cast steel or sintered
steel.
13. A fuel injection system, comprising: a plug-in pump comprising:
a cylinder having a cavity, and a pump housing, a movable piston
arranged in the cavity of the cylinder, wherein a first end of the
piston delimits a pump chamber, and a second end of the piston is
connected to a drive device for the piston, an inlet valve arranged
in the cylinder, wherein the inlet valve connects the pump chamber
to a feed line for a first fluid, and an outlet valve that connects
the pump chamber to an outlet, wherein the pump housing has a
cavity that forms (a) a first chamber connected to a feed line for
the first fluid, and at least one second chamber separated from the
first chamber and connected to a fluid system of a second fluid,
wherein the first chamber is fluidically sealed off with respect to
the second chamber.
14. The fuel injection system of claim 13, wherein the second end
of the piston of the plug-in pump is connected to or formed
integrally with an intermediate piece that transmits a movement of
the drive device to the piston.
15. The fuel injection system of claim 14, wherein the intermediate
piece includes a first section that projects into the first
chamber, a third section that projects into the second chamber, and
a second section that connects the first section and the third
section and projects through a connecting region formed in the
cavity between the first chamber and the second chamber.
16. The fuel injection system of claim 15, wherein: the connecting
region has a shape of a hollow cylinder having an inside diameter
that corresponds substantially to an outside diameter of the second
section, and at least one of the inner wall of the connecting
region and the second section has a sealing element that prevents
the first and second fluids from mixing with each other.
17. The fuel injection system of claim 13, wherein the plug-in pump
comprises at least one spring element arranged in at least one of
the first chamber and the second chamber, wherein the at least one
spring element moves the piston and the intermediate piece in a
direction in which the inlet valve connects the feed line to the
pump chamber.
18. The fuel injection system of claim 13, wherein the plug-in pump
comprises a spring element in the first chamber, wherein the spring
element moves the piston and the intermediate piece in a direction
in which the inlet valve connects the feed line to the pump
chamber, and wherein the spring element is supported on an
underside of the cylinder head and on a spring holder connected to
an end of the intermediate piece facing the second end of the
piston.
19. The fuel injection system of claim 13, wherein the plug-in pump
comprises a spring element in the second chamber, wherein the
spring element moves the piston and the intermediate piece in a
direction in which the inlet valve connects the feed line to the
pump chamber, and wherein the spring element is supported on an
underside of the connecting region and on a spring holder connected
to an end of the intermediate piece facing the drive device.
20. The fuel injection system of claim 13, wherein: the first fluid
is carried by the feed line and connecting lines in the pump
housing into an annular passage, the annular passage is formed in
the connecting region between the cylinder and the housing, and at
least one side wall of the annular passage is formed by an outer
side of the cylinder and at least one side wall of the annular
passage is formed by an outer side of the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2013/077331 filed Dec. 19,
2013, which designates the United States of America, and claims
priority to DE Application No. 10 2012 224 317.8 filed Dec. 21,
2012, the contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The invention relates to a plug-in pump having a cylinder
and a pump housing. The cylinder has a cavity, in which a movable
piston is accommodated, wherein one end of the piston delimits a
pump chamber, and the other end of the piston is connected to a
drive for the piston. Also arranged in the cylinder are an inlet
valve, which connects the pump chamber to a feed line for a fluid,
and an outlet valve, which connects the pump chamber to an outlet.
The pump housing has a cavity which is divided into a first
chamber, a second chamber, which is separated from the first
chamber, and a connecting region, which connects the first chamber
and the second chamber, wherein different fluids flow in the two
chambers.
BACKGROUND
[0003] DE 10 2009 000 857 A1 discloses a plug-in pump for a fuel
injection system. The plug-in pump has a piston, which is arranged
in a cavity of a cylinder head and is driven by a camshaft via a
roller tappet. The piston can be moved in a linear fashion in the
cavity in order to open an inlet for the fuel into a pump working
chamber in a suction stroke. During a subsequent delivery stroke,
the fuel is passed out of the pump working chamber through a pump
outlet to another unit of the engine. At its end remote from the
pump working chamber, the pump piston has a sealing element
surrounding it, which seals off the piston with respect to the
engine oil, said oil lubricating the camshaft, for example, in
order to prevent fuel from being able to get into the engine oil
and vice versa.
[0004] Conventional seals, e.g. combination seals of the kind known
in the prior art, are often incapable of preventing fuel from
getting into the engine oil and vice versa with sufficient
reliability, and therefore it is not always possible to meet the
demands made by engine designers on such pumps.
SUMMARY
[0005] One embodiment provides a plug-in pump having a cylinder and
a pump housing, wherein the cylinder has a cavity, in which a
movable piston is accommodated, wherein a first end of the piston
delimits a pump chamber, and a second end of the piston is
connected to a drive device for the piston, an inlet valve is
arranged in the cylinder, which inlet valve connects the pump
chamber to a feed line for a first fluid, and an outlet valve,
which connects the pump chamber to an outlet, wherein the pump
housing has a cavity which forms a first chamber, which is
connected to a feed line for the first fluid, and at least one
second chamber, which is separated from the first chamber and is
connected to a fluid system of a second fluid, wherein the first
chamber is fluidically sealed off with respect to the second
chamber.
[0006] In a further embodiment, the second end of the piston is
connected to or formed integrally with an intermediate piece, which
transmits a movement of the drive device to the piston.
[0007] In a further embodiment, the intermediate piece has a first
section, which projects into the first chamber, a third section,
which projects into the second chamber, and a second section, which
connects the first section and the third section and projects
through a connecting region, formed in the cavity, between the
first chamber and the second chamber.
[0008] In a further embodiment, the connecting region has the shape
of a hollow cylinder, having an inside diameter which corresponds
substantially to an outside diameter of the second section, and
wherein the inner wall of the connecting region and/or the second
section has/have a sealing element, which prevents the first and
second fluid from mixing.
[0009] In a further embodiment, a spring element or spring elements
is/are arranged in the first chamber and/or in the second chamber,
which spring element/s move/s the piston and the intermediate piece
in a direction in which the inlet valve connects the feed line to
the pump chamber.
[0010] In a further embodiment, the spring element in the first
chamber is supported on an underside of the cylinder head and on a
spring holder, which is connected to an end of the intermediate
piece which faces the second end of the piston.
[0011] In a further embodiment, the spring element in the second
chamber is supported on an underside of the connecting region and
on a spring holder, which is connected to an end of the
intermediate piece which faces the drive device.
[0012] In a further embodiment, the first fluid is carried by the
feed line and connecting lines in the pump housing into an annular
passage, wherein the annular passage is formed in the connecting
region between the cylinder and the housing, and at least one side
wall of the annular passage is formed by an outer side of the
cylinder and at least one side wall of the annular passage is
formed by an outer side of the housing.
[0013] In a further embodiment, the drive device is a camshaft,
wherein a cam of the camshaft preferably acts on a roller tappet,
and the roller tappet converts a rotary motion of the camshaft into
a linear motion of the piston.
[0014] Another embodiment provides a plug-in pump having at least
one of the following features: the inlet valve is a digital inlet
valve; the first fluid is a fuel and the second fluid is a
lubricating oil; and the cylinder is formed from steel and the
housing is formed from cast steel or sintered steel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Example embodiments of the invention are explained in
greater detail below with reference to the drawings, in which:
[0016] FIG. 1 shows a section through a plug-in pump according to
one embodiment; and
[0017] FIG. 2 shows another section through the plug-in pump in
FIG. 1.
DETAILED DESCRIPTION
[0018] Embodiments of the invention provide a plug-in pump which,
with greater reliability than hitherto known, fluidically separates
a region of the pump containing a first fluid from a region
interacting with the pump and containing a second fluid.
[0019] Some embodiments provide a plug-in pump having a cylinder
and a separate pump housing, wherein the cylinder has a cavity, in
which a movable piston is accommodated, preferably in a sealing
manner. The piston can move at least in a linear fashion in the
cavity, the cavity forming a guide for the piston with a shape and
an inside diameter which corresponds substantially to the shape and
outside diameter of the piston.
[0020] A first end of the piston, which faces the cylinder,
delimits a pump chamber. That is to say that the first end
completely closes the pump working chamber in a first end position,
before the beginning of a suction stroke of the piston, since the
first end of the piston is situated in the pump working space
before the beginning of the suction stroke and fills said chamber
essentially completely. After the beginning of the suction stroke,
the piston moves in a direction away from the cylinder and out of
the pump chamber, with the result that fuel can now flow into the
pump chamber through an open inlet valve. When the suction stroke
is complete, the piston is situated in a second end position, and
the pump working chamber has its maximum volume. During the
subsequent delivery stroke of the piston back into the first
position, the inlet valve is closed and the fuel in the pump
working chamber is forced out of the pump working chamber through
an outlet valve.
[0021] In this case, the inlet and the outlet valve are arranged in
the cylinder, and the inlet valve connects the pump working chamber
to a feed line for a first fluid.
[0022] The second end of the piston is connected to a drive device
for the piston, which moves the piston in a linear fashion in the
cavity from the second position to the first position and vice
versa. The drive device can be a camshaft of an engine, for
example.
[0023] The pump housing of the plug-in pump has a cavity which
forms at least one first chamber and one second chamber, which is
separated from the first chamber. The first chamber is fluidically
sealed off with respect to the second chamber.
[0024] The pump housing is connected to the cylinder and preferably
surrounds part of the cylinder, in particular a cylindrical part of
the cylinder, in which the cavity for the piston is at least
partially formed. This part of the cylinder can project into the
first cavity of the pump housing, for example. The housing and/or
the cylinder can have a sealing element, which prevents the first
fluid that enters the first chamber from escaping from the plug-in
pump through the joint between the cylinder and the pump
housing.
[0025] The first fluid can flow through the feed line in the pump
housing into an annular passage, for example, formed in the pump
housing. From the annular passage in the pump housing, the first
fluid can flow through connecting passages, likewise formed in the
pump housing, into a further annular passage, which is formed in
the connecting region between the cylinder and the pump housing.
Here, at least one side wall of said annular passage can be formed
by an outer side of the cylinder and at least one other side wall
can be formed by an outer side of the housing. For this purpose, a
groove can be introduced into the cylinder and/or the pump housing,
for example, in at least one of the facing ends of the cylinder and
the pump housing, said groove becoming a closed passage through the
connection of the cylinder to the pump housing.
[0026] From the annular passage formed in the connecting region of
the cylinder and the pump housing, the fluid can flow in feed
passages which carry the fluid to a supply chamber for the fluid in
the region of the inlet valve for the pump working chamber. These
feed passages can additionally be connected to return passages,
which carry excess fluid back into a supply container.
[0027] The inlet valve is connected to an actuator, which controls
the opening and closure of the inlet valve, which is preferably a
digital inlet valve (DIV), according to specifiable criteria.
[0028] The second end of the piston can be connected to an
intermediate piece, which transmits the movements of the drive unit
to the piston. In this context, "can be connected" can mean that
there are two separate parts, the mutually opposite end faces of
which touch, abutting one another, or that the piston and the
intermediate piece are formed integrally, or that the piston is
connected by positive engagement and/or nonpositive engagement, for
example, to the intermediate piece.
[0029] The intermediate piece is arranged in the cavity of the pump
housing and extends from the first chamber into the second chamber.
The intermediate piece can be a cylindrical body, for example,
having a first section, which projects into the first chamber and
rests by means of the end facing the cylinder on the second end of
the piston, and a third section, which projects into or through the
second chamber and makes direct or indirect contact with the drive
device.
[0030] Between the first and the third section, the intermediate
piece can have a second section, which connects the first section
to the third section and projects through a connecting region,
formed in the cavity of the pump housing, between the first chamber
and the second chamber.
[0031] The connecting region can have the shape of a hollow
cylinder, having an inside diameter which is preferably constant
over the length thereof and corresponds substantially to an outside
diameter of the second section. A sealing element can be fitted in
the inner wall of the connecting region and/or on a surface of the
outer circumference of the second section of the intermediate piece
in order to separate the first chamber fluidically from the second
chamber. The sealing element can be a simple scraper or can be a
sealing ring, for example.
[0032] Respective spring elements can be arranged in the first
chamber and/or in the second chamber of the cavity of the pump
housing. The spring element or elements can be spiral springs, for
example, which surround the intermediate piece or a part of the
first section of the intermediate piece and/or a part of the third
section of the intermediate piece. During the delivery stroke of
the piston, the spring element or elements are subjected to a load
by the drive device and, after the end of the delivery stroke, push
the intermediate piece back in the opposite direction, i.e. bring
about or assist the suction stroke of the piston when the latter
follows the movement of the intermediate piece.
[0033] In the case of a spring element in the first chamber and
another spring element in the second chamber, the spring forces of
the two spring elements act in the same direction. This has the
advantage that the individual spring element can be made smaller,
which can lead to a smaller overall length and/or a smaller overall
circumference of the pump housing.
[0034] The spring element in the first chamber can be supported on
underside of the cylinder or an inner wall of the end of the cavity
of the pump housing facing the cylinder and on the end of the
intermediate piece facing the piston, for example. For this
purpose, the intermediate piece can have a spring holder, i.e. an
encircling widened portion, which is connected to the intermediate
piece, being fitted onto the intermediate piece for example, or is
partially formed by the intermediate piece, on which widened
portion the end of the spring element remote from the cylinder can
be supported.
[0035] The spring element in the second chamber can be supported on
an underside of the connecting region and on a spring holder, which
is connected to the end of the intermediate piece facing the drive
device, for example.
[0036] The end of the pump housing facing the drive device can form
a guide bushing for a drive slide, having a roller tappet which is
moved by a cam of a camshaft. The drive slide can slide up and down
in the guide bushing and thereby move the intermediate piece and
impose a load on the spring elements. In this case, the spring
holder for the spring element in the second chamber of the pump
housing can be formed by the end of the intermediate piece facing
the drive device, partially formed by the drive slide or connected
to the latter.
[0037] As already mentioned, the drive device can be a camshaft of
an internal combustion engine, wherein a cam of the camshaft
preferably acts on a roller tappet, and the roller tappet converts
a rotary motion of the camshaft into a linear motion of the
intermediate piece and of the piston.
[0038] The first fluid is preferably a fuel for an internal
combustion engine, e.g. gasoline or diesel or gas, and the second
fluid is preferably a lubricating oil.
[0039] The cylinder can be formed from a high-grade steel, having a
high strength, while the pump housing can be formed from cast steel
or sintered steel, for example, having a lower strength than that
of the cylinder. It is thereby possible to save on materials and
processing costs and on weight. Moreover, the separate pump housing
can be combined in a modular manner with cylinders for different
combustibles, leading to further savings and, at the same time, to
a desired standardization of components.
[0040] Throughout the description and the claims, the term "a" is
not to be taken as restrictive. If this term is intended as a
numerical indicator, this is made clear in the description and the
claims by terms such as "a single". This means that the term "a" in
this description can, but does not necessarily have to, be read as
"at least one".
[0041] FIG. 1 shows a section through a plug-in pump 1 according to
one embodiment. The plug-in pump 1 comprises or consists of a
cylinder 2 and of a separate pump housing 3.
[0042] The cylinder 2 has a first part 2b, with a surface 2a which
faces the pump housing. The first part 2b of the cylinder 2 has an
inlet valve 7 with an actuator 9, which brings about opening and
closure of the inlet valve 7, an outlet valve 8 and a pump working
chamber 6. The pump working chamber 6 is part of a cavity 4.
[0043] The cylinder 2 furthermore has a second part 2c, which is
formed jointly with the first part 2b and extends the first part 2b
on an opposite side from the actuator 9. The second part 2c
likewise has the cavity 4. The second part 2c has an outer
circumference which is smaller than the outer circumference of the
first part 2b and extends the first part 2b of the cylinder 2 in a
central region.
[0044] In the second part 2c, the cavity 4 is a through hole, and
in the first part 2b a blind hole which opens into the pump working
chamber 6. Arranged in the cavity 4 is a piston 5, with a first end
5a, which has a shape that corresponds substantially to the shape
of the pump working chamber 6, and a second end 5b, which projects
beyond the end of the second part 2c of the cylinder 2. The piston
5 has an outer circumference which corresponds substantially to the
inner circumference of the cavity 4. The piston 5 can move in a
linear fashion in the cavity 4 into a first end position, in which
it completely fills the pump working chamber 6, and into a second
end position, in which the piston 5 is completely outside the pump
working chamber 6. In the second end position, the piston 5 or the
end 5a thereof facing the pump working chamber 6 forms a rear wall
of the pump working chamber 6.
[0045] The plug-in pump 1 furthermore has a pump housing 3, having
an end 3a facing the cylinder. The pump housing 3 has a cavity 10,
which forms a first chamber 11, a second chamber 13 and a
connecting region 15, which connects the first chamber 11 to the
second chamber 13.
[0046] The pump housing 3 furthermore comprises a feed line 12 for
a fuel and, at its end remote from the cylinder 2, a guide bushing
26 for a slide 27, which comprises a roller tappet 28, which is
moved in a linear fashion in the guide bushing 26 by a cam of a
camshaft (not shown).
[0047] The second part 2c of the cylinder 2 projects into the first
chamber 11. In order to seal off the engagement of the second part
2c of the cylinder 2 in the first chamber 11 of the pump housing 3,
the cylinder 2 has an encircling engagement element 29 in the
region of the transition of the first part 2b to the second part
2c, and the pump housing 3 has a sealing element 30 in the region
of the contact of the engagement element 29 with an inner wall of
the cavity 10 of the pump housing 3.
[0048] Arranged in the cavity 10 of the pump housing 3 is an
intermediate piece 14, which connects the piston 5 to the drive
device and the slide 27 to the roller tappet 28 and thus transmits
the driving force of the drive device to the piston 5.
[0049] The intermediate piece 14 has a first section 14a, the end
of which facing the cylinder 2 rests against the second end 5b of
the piston 5 or is connected positively and/or nonpositively
thereto. Adjoining the first section 14a is a second section 14b,
which projects through a connecting region 15 formed in the cavity
10. In the illustrative embodiment shown, the connecting region 15
is of hollow-cylindrical design, having an inside diameter which
corresponds substantially to the outside diameter of the second
section 14b, which is likewise of cylindrical design. The second
section 14b has a sealing element 16 in the form of a scraper,
which prevents a fluid situated in the first chamber 11 from being
able to mix with a fluid present in the second chamber 13. This
means that the connecting region 15 together with the second
section 14b of the intermediate piece 14 seal off the first chamber
11 and the second chamber 13 fluidically from one another.
Adjoining the second section 14b is a third section 14c, which is
arranged in the second chamber 13 and is connected directly or
indirectly to the roller tappet 28 or the slide 27.
[0050] Arranged in the first chamber 11 is a spring element 17,
which is supported on the outer side 2a of the cylinder 2, said
outer side facing the pump housing 3, and on a spring holder 19,
which is fitted onto the end of the intermediate piece 14 facing
the piston 5 in the illustrative embodiment shown. The spring
element 17, which is a spiral spring that surrounds the second part
2c of the cylinder, is compressed during a movement of the piston 5
into the pump working chamber 6, a delivery stroke of the piston 5,
and can expand again after the ending of the delivery stroke and,
in the process, move and/or assist the piston 5 in a suction stroke
movement. The second part 2c forms a guide for the spring element
17.
[0051] Arranged in the second chamber 13 is a spring element 18,
which is supported on an underside of the intermediate region 15
and on a spring holder 21, wherein the spring holder 21 is
connected to the slide 27 and/or to the end of the intermediate
piece 14 facing the drive device. Spring element 18 is also
compressed during the delivery stroke of the plug-in pump 1, and
can then expand again and carry out and/or assist the suction
stroke of the plug-in pump 1. As shown, the intermediate region 15
can be formed partially as a cylindrical sleeve which projects into
the second chamber 13 and is surrounded by spring element 18, the
sleeve thus forming a guide for spring element 18.
[0052] Another section through the plug-in pump 1 of FIG. 1 is
shown in FIG. 2, showing a flow path of the fuel from the feed line
(not visible in this view) to the inlet valve 7 by way of example.
From the feed line 12, the fuel is carried into an annular passage
20a, which is formed in the pump housing 3 and extends in the pump
housing 3 around the cavity 10 at the level of the feed line 12.
From the annular passage 20a, the fuel is carried via feed passages
22 into the annular passage 20 formed between the cylinder 2 and
the pump housing 3. Connecting passages 23 lead from the annular
passage 20 to delivery passages 24, which carry the fuel into a
fuel supply chamber 25 situated ahead of the inlet valve 7. The
delivery passages 24 are connected to return passages, which carry
fuel that is not needed back into a tank.
LIST OF REFERENCE SIGNS
[0053] 1 plug-in pump [0054] 2 cylinder [0055] 2a end of cylinder
[0056] 2b first part of cylinder [0057] 2c second part of cylinder
[0058] 3 pump housing [0059] 3a end of pump housing [0060] 4 cavity
of cylinder [0061] 5 piston [0062] 5a first end of piston [0063] 5b
second end of piston [0064] 6 pump working chamber [0065] 7 inlet
valve [0066] 8 outlet valve [0067] 8a outlet [0068] 9 actuator
[0069] 10 cavity of pump housing [0070] 11 first chamber [0071] 12
fuel feed line [0072] 13 second chamber [0073] 14 intermediate
piece [0074] 14a first section [0075] 14b second section [0076] 14c
third section [0077] 15 connecting region [0078] 16 sealing element
[0079] 17 spring element [0080] 18 spring element [0081] 19 spring
holder [0082] 20 annular passage [0083] 20a annular passage [0084]
21 spring holder [0085] 22 feed passage [0086] 23 connecting
passage [0087] 24 delivery passage [0088] 25 fuel supply chamber
[0089] 26 guide bushing [0090] 27 slide [0091] 28 roller tappet
[0092] 29 engagement element [0093] 30 sealing element
* * * * *